Enable proxy_cache_revalidate by default

[yhaliaw]

Overview

Enable proxy-cache-revalidate by default.

Rationale

This was requested for the k8s content-cache and makes sense for the this charm as well.

Checklist

• The charm style guide was applied
• The contributing guide was applied
• The changes are compliant with ISD054 - Managing Charm Complexity
• The documentation is generated using src-docs
• The documentation for charmhub is updated
• The PR is tagged with appropriate label (urgent, trivial, complex)
• The docs/changelog.md is updated with user-relevant changes.

[github-actions]

Test coverage for f9998c9

Name            Stmts   Miss Branch BrPart  Cover   Missing
-----------------------------------------------------------
src/charm.py       47      0      6      0   100%
src/errors.py       1      0      0      0   100%
src/state.py      115      0     28      0   100%
-----------------------------------------------------------
TOTAL             163      0     34      0   100%

Static code analysis report

Run started:2025-01-10 11:14:11.555662

Test results:
  No issues identified.

Code scanned:
  Total lines of code: 938
  Total lines skipped (#nosec): 0
  Total potential issues skipped due to specifically being disabled (e.g., #nosec BXXX): 0

Run metrics:
  Total issues (by severity):
  	Undefined: 0
  	Low: 0
  	Medium: 0
  	High: 0
  Total issues (by confidence):
  	Undefined: 0
  	Low: 0
  	Medium: 0
  	High: 0
Files skipped (0):